Diesel engine working of dual combustion cycle has a stroke volume of 0.085 m³ and a compression ratio of 15:1. The fuel has a calorific value of 43,890 kJ/kg. The initial pressure and temperature are 1 bar and 100 degrees C. The maximum pressure is 65 bar. Find the thermal efficiency. Assume Cp = 1.05 and Cv = 0.71 and cut-off ratio is 5% of stroke volume.